Recorded at the CEPR Paris Symposium. At COPs or the WEF, we regularly hear about ambitious tree-planting initiatives. These massive programs have been praised as a way to motivate entire communities to join the fight against climate change, but do we know what their impact on the environment or the economy would be? An ingenious piece of research that evaluates a century-old environmental policy in the US gives us a valuable new insight into what planting trees, if done carefully, can achieve. Florian Grosset-Touba spoke to Tim Phillips about the history of tree-planting programmes, where and how to plant them, and the potential impact on the climate and the economy.